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But in the 15 years that have passed since the Disney Channel franchise first burst onto our screens, the star's looks - or rather, our obsession with them - have at times threatened to overshadow his acting work.
Never has this been more evident than last month, when the 33-year-old appeared in a video to promote Bill Nye's Earth Day! The Musical.
Zac is only in the video for a matter of seconds but that didn't stop thousands of fans from scrutinising and obsessing over his jawline. Even doctors tried to "explain" to concerned fans why Zac looks the way he does.
One TikTok video, which accumulated more than 5.6m views and 32.3k comments, left people wondering whether Zac had undergone cosmetic procedures.
"It's either too much filler OR he's wearing David Hasslehoff's face as a mask."
"He's definitely had filler. Sad".
"Omg he's had surgery big time".
But isn't the question we should be asking: why do we care so much about Zac's changing appearance and whether or not he's had plastic surgery?
Digital Expert Harvey Morton says the obsession with the physical appearance of celebrities and their changing appearances is "unhealthy".
"Putting our emphasis on looks, such as dissecting the jawline of Zac, gives us all an unhealthy view of what it takes to be considered beautiful," he tells Tyla.
"When a photograph of Zac Efron appears and his jaw seems slightly squarer, there is a mountain of commentary on whether he has had plastic surgery. It is as if we are permitted to hold an opinion publicly and tactlessly about another human being, forgetting completely their feelings and self-esteem.
"I guess the only reason this is surprising is because Zac is male, female celebrities have lived with such comments for decades," he adds.
Harvey also compared the reaction to Zac's face to the highly-criticised Channel 5 documentary about Charlotte Crosby's face which was pulled days after it aired due to widespread backlash. "At a time where kindness is more necessary than ever, this feels like a disappointing reaction,"
Psychologist Zoe Clews also notes that female celebrities have had to deal with their appearance and rumoured cosmetic procedures being unpicked by the general public.
"We live in a society where people - and particularly women - are criticised for ageing and are then equally criticised for having the procedures that make them look younger. They can't really win."
In fact, Zoe suggests there may even be more stigma around plastic surgery for men than women.
"Despite the absolute battering that female celebrities get for having plastic surgery, there's even more stigma around men and surgery. There's this perception that 'real men' should be content with the face or body that life dealt them and just get on with it.
"As a result, men who are perceived to be unhappy with their appearance risk being labelled by some to be in some way insecure or weak. "
Almost a year has passed since Zac debuted his 'dad bod' in his Netflix series Down To Earth; the positive reaction to his body, compared to the plastic surgery speculation, was stark.
Zoe, who specialises in PTSD, trauma and anxiety, said the backlash against Zac's 'new face' face was "particularly vicious".
Last week Zac uploaded a new picture from behind the scenes of Down To Earth to Instagram and many fans claimed his face looked "normal" again. One commenter even wrote: "There's the jawline we know and love!"
A second fan added: "So your face is normal!"
Zoe explained that there is also a "sense of wonder" from the public when celebrities who are already considered "super-good look" have cosmetic treatments. She adds: "People don't like people changing. Efron's fans have become used to him looking a certain way."
Just like regular people, celebrities will look different to how they did at the start of their careers and Zoe says to protect our own mental health as well as for celebs, people should take a moment to think before commenting on someone's "new face."
She added: "Let's not forget that if we're always hyper-focused on how someone else looks we will also turn that mirror onto ourselves. Not only does that make us feel discontentment, that permanent immersion in our obsession with others also means we're missing out on a large and positive part of our own lives."
Featured Image Credit: Earth Day! The Musical/ Facebook
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